title: The association between low-dose aspirin use and the incidence of colorectal cancer: a nationwide cohort study.
abstract: BACKGROUND
  Considerable evidence suggests that aspirin has a chemopreventive effect on colorectal cancer (CRC). However, optimal dose and treatment duration have not been defined, and data on the effects of low-dose aspirin are contradictory.
  
  
  OBJECTIVE
  To determine if the incidence of CRC in patients with low-dose aspirin use was lower than in those without aspirin use.
  
  
  METHODS
  From Taiwan's National Health Insurance research database, aspirin users (n = 1985) were defined as adults (age ≥20 years) with at least 3.5 years of regular low-dose aspirin use (50-150 mg per day) between 1998 and 2002. Non-users (n = 7940) were those who did not use aspirin and were matched 4:1 with the user group by age, gender, date of ambulatory care (index date), and presence of known risk factors for cardiovascular disease (including hypertension, diabetes mellitus and hyperlipidaemia). Follow-up of the two study groups was made until the end of 2010, and incidences and hazard ratios of colorectal cancer were determined.
  
  
  RESULTS
  During a median follow-up period of 8.9 years, 129 non-users and 14 users developed CRC, corresponding to incidence rates of 180.43 and 79.42 per 100,000 person-years respectively. Duration of aspirin use among users ranged from 3.5 to 12.6 years (mean 8.7 years). The multivariate-adjusted hazard ratio for CRC was 0.5 (95% confidence interval 0.28-0.87) among users as compared with non-users.
  
  
  CONCLUSIONS
  Long-term use of low-dose aspirin appears to be associated with a lower incidence of CRC in patients with high cardiovascular risk. Further randomised clinical trials are necessary to confirm these findings.
authors.affiliation: Division of Hematology-Oncology, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: W-K
authors.initials: WK
authors.lastname: Huang
authors.forename: M-J
authors.initials: MJ
authors.lastname: Chiou
authors.forename: K-H
authors.initials: KH
authors.lastname: Yu
authors.forename: Y-C
authors.initials: YC
authors.lastname: Lin
authors.forename: T-S
authors.initials: TS
authors.lastname: Yang
authors.forename: J-S
authors.initials: JS
authors.lastname: Chen
authors.forename: C-F
authors.initials: CF
authors.lastname: Kuo
authors.forename: L-C
authors.initials: LC
authors.lastname: See
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage* / Q000494:pharmacology; D001241:Aspirin / Q000008:administration & dosage* / Q000494:pharmacology; D002318:Cardiovascular Diseases / Q000188:drug therapy*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D013624:Taiwan; D013997:Time Factors; D055815:Young Adult
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D001241:Aspirin